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噪声下基于耳蜗基底膜分频特性的声源定位 被引量:1
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作者 张毅 许方煜 罗元 《重庆邮电大学学报(自然科学版)》 CSCD 北大核心 2015年第6期803-808,共6页
在人与人交流中,人耳能很好地定位出周围声音的位置,而在声源定位技术里,基于传统麦克风声源定位在噪声环境下无法精确地定位出声源。根据人耳能准确地辨别出声源这一特性,提出一种在噪声下基于人耳耳蜗基底膜分频特性的声源定位方法。... 在人与人交流中,人耳能很好地定位出周围声音的位置,而在声源定位技术里,基于传统麦克风声源定位在噪声环境下无法精确地定位出声源。根据人耳能准确地辨别出声源这一特性,提出一种在噪声下基于人耳耳蜗基底膜分频特性的声源定位方法。该方法是利用多个麦克风对声源信号进行采集,将采集到的信号通过基底膜滤波器进行滤波、除去与声源无关的噪声,运用空间映射互相关方法对声源进行定位。该方法所定位出的声源位置比传统声源定位技术所定位的位置误差小、精准度高。实验结果表明,噪声环境下基于耳蜗基底膜分频特性的声源定位比基于传统麦克风声源定位技术更接近声源的真实位置;噪声环境下基于耳蜗基底膜分频特性的声源定位具有更高的精度与更好的鲁棒性。 展开更多
关键词 声源定位 耳蜗基底膜特性 分频特性 时间差
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基于谐振积分器的分频检测算法 被引量:1
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作者 汤赐 涂春鸣 罗安 《电力自动化设备》 EI CSCD 北大核心 2010年第7期45-49,共5页
实际工程应用只需要考虑对有限的几次谐波进行治理即可,考虑到谐波治理工程的要求和并联型有源电力滤波器容量的大小,对并联型有源电力滤波器的分频检测算法进行了研究。通过对谐振积分器基本原理的分析,利用谐振积分器所具有的选频特性... 实际工程应用只需要考虑对有限的几次谐波进行治理即可,考虑到谐波治理工程的要求和并联型有源电力滤波器容量的大小,对并联型有源电力滤波器的分频检测算法进行了研究。通过对谐振积分器基本原理的分析,利用谐振积分器所具有的选频特性,提出了一种基于谐振积分器的分频检测算法。该检测算法既可省去锁相环及三角函数计算,也无需进行αβ坐标系变换到dq坐标系及其反变换的计算。相关实验结果验证了基于谐振积分器的分频检测算法的有效性。 展开更多
关键词 有源电力滤波器 检测算法 谐振积分器 分频特性 分频检测算法
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Frequency Response Computation and Error Analyses 被引量:5
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作者 姚晓先 林凡 《Journal of Beijing Institute of Technology》 EI CAS 1999年第4期381-385,共5页
Aim To derive the error formulae for the algorithm of frequency response computation. Methods This algorithm was introduced theoretically, the error sources of the algorithm were analyzed and the formulae of the mai... Aim To derive the error formulae for the algorithm of frequency response computation. Methods This algorithm was introduced theoretically, the error sources of the algorithm were analyzed and the formulae of the main error were derived. Results The repeatability and stability of the processing results of the algorithm are better than those measured by 1250 Frequency Analysor. Conclusion The error formulae derived are theoretically right and practically valid. 展开更多
关键词 frequency response error analysis computer aided test
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Spectral analysis of bowel sounds in intestinal obstruction using an electronic stethoscope 被引量:14
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作者 Siok Siong Ching Yih Kai Tan 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第33期4585-4592,共8页
AIM: To determine the value of bowel sounds analysis using an electronic stethoscope to support a clinical diagnosis of intestinal obstruction. METHODS: Subjects were patients who presented with a diagnosis of possibl... AIM: To determine the value of bowel sounds analysis using an electronic stethoscope to support a clinical diagnosis of intestinal obstruction. METHODS: Subjects were patients who presented with a diagnosis of possible intestinal obstruction based on symptoms, signs, and radiological findings. A 3MTH Littmann Model 4100 electronic stethoscope was used in this study. With the patients lying supine, six 8-second recordings of bowel sounds were taken from each patient from the lower abdomen. The recordings were analysed for sound duration, soundto-sound interval, dominant frequency, and peak frequency. Clinical and radiological data were reviewed and the patients were classified as having either acute, subacute, or no bowel obstruction. Comparison of bowel sound characteristics was made between these subgroups of patients. In the presence of an obstruction, the site of obstruction was identified and bowel calibre was also measured to correlate with bowel sounds. RESULTS: A total of 71 patients were studied during the period July 2009 to January 2011. Forty patientshad acute bowel obstruction (27 small bowel obstruction and 13 large bowel obstruction), 11 had subacute bowel obstruction (eight in the small bowel and three in large bowel) and 20 had no bowel obstruction (diagnoses of other conditions were made). Twenty-five patients received surgical intervention (35.2%) during the same admission for acute abdominal conditions. A total of 426 recordings were made and 420 recordings were used for analysis. There was no significant difference in sound-to-sound interval, dominant frequency, and peak frequency among patients with acute bowel obstruction, subacute bowel obstruction, and no bowel obstruction. In acute large bowel obstruction, the sound duration was significantly longer (median 0.81 s vs 0.55 s, P = 0.021) and the dominant frequency was significantly higher (median 440 Hz vs 288 Hz, P = 0.003) when compared to acute small bowel obstruction. No significant difference was seen between acute large bowel obstruction and large bowel pseudoobstruction. For patients with small bowel obstruction, the sound-to-sound interval was significantly longer in those who subsequently underwent surgery compared with those treated non-operatively (median 1.29 s vs 0.63 s, P < 0.001). There was no correlation between bowel calibre and bowel sound characteristics in both acute small bowel obstruction and acute large bowel obstruction. CONCLUSION: Auscultation of bowel sounds is nonspecific for diagnosing bowel obstruction. Differences in sound characteristics between large bowel and small bowel obstruction may help determine the likely site of obstruction. 展开更多
关键词 Bowel sounds Intestinal obstruction Spectral analysis Electronic stethoscope
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A Fast Algorithm for Improving the Visual Distance in Fog
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作者 YANG Wei XIAO Zhi-tao +1 位作者 YU Jian YAN Zhi-jie 《Semiconductor Photonics and Technology》 CAS 2009年第4期241-246,共6页
Images captured outdoor usually degenerate because of the bad weather conditions,among which fog,one of the widespread phenomena,affects the video quality greatly.The physical features of fog make the video blurred an... Images captured outdoor usually degenerate because of the bad weather conditions,among which fog,one of the widespread phenomena,affects the video quality greatly.The physical features of fog make the video blurred and the visible distance shortened,seriously impairing the reliability of the video system.In order to satisfy the requirement of image processing in real-time,the normal distribution curve fitting technology is used to fit the histogram of the sky part and the region growing method is used to segment the region of sky.As for the non-sky part,a method of self-adaptive interpolation to equalize the histogram is adopted to enhance the contrast of the images.Experiment results show that the method works well and will not cause block effect. 展开更多
关键词 fog image INTERPOLATION region growing histogram equalization fast algorithm normaldistribution
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Frequency and Correlation Characteristic of the Hopf Bifurcation Chemical Oscillatory Patterns
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《Journal of Chemistry and Chemical Engineering》 2012年第3期284-291,共8页
The Belousov-Zhabotinski type of chemical reactions was studied. Dynamics of the unperturbed oscillating chemical system and subject to the external perturbations is considered. The system response to the external per... The Belousov-Zhabotinski type of chemical reactions was studied. Dynamics of the unperturbed oscillating chemical system and subject to the external perturbations is considered. The system response to the external periodic perturbation near the Hopf bifurcation point has been monitored. As a response to the external periodic perturbation of system, one obtains the synchronization oscillations, two-, three-and multiperiodic ones as well as obtain two types of chaos. The kinetic of such reactions is analyzed by time series. The Fourier transforms were used to analyze the frequency characteristics of the synchronized and chaotic states giving the different harmonic spectra. As further statistical characteristics the winding numbers and variation values of trajectories are calculated using a rotational model of processes in relation to the coherence parameter joint with perturbation period. For chaotic states the autocorrelation functions and correlation dimensions, which form an approximation of a fractal dimension D, have been calculated. Additionally, Lyapunov exponents were computed. Their positive values confirmed chaotic behavior. 展开更多
关键词 OSCILLATIONS Fourier spectrum circle map correlation dimension Lyapunov spectrum.
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Symmetry of the Point Spectrum of Upper Triangular Infinite Dimensional Hamiltonian Operators 被引量:2
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作者 WANG Hua Alatancang HUANG dun die 《Journal of Mathematical Research and Exposition》 CSCD 2009年第5期907-912,共6页
In this paper, by using characterization of the point spectrum of the upper triangular infinite dimensional Hamiltonian operator H, a necessary and sufficient condition is obtained on the symmetry of σP(A) and σ1/... In this paper, by using characterization of the point spectrum of the upper triangular infinite dimensional Hamiltonian operator H, a necessary and sufficient condition is obtained on the symmetry of σP(A) and σ1/P(-A^*) with respect to the imaginary axis. Then the symmetry of the point spectrum of H is given, and several examples are presented to illustrate the results. 展开更多
关键词 non-self-adjoint operator infinite dimensional Hamiltonian operator point spectrum symmetry.
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Complexity and characteristic frequency studies in ECG signals of mice based on multiple scale factors 被引量:1
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作者 YANG XiaoDong HE AiJun +2 位作者 LIU Peng SUN TongFeng NING XinBao 《Science China(Life Sciences)》 SCIE CAS 2011年第6期544-552,共9页
Existing methods of physiological signal analysis based on nonlinear dynamic theories only examine the complexity difference of the signals under a single sampling frequency.We developed a technique to measure the mul... Existing methods of physiological signal analysis based on nonlinear dynamic theories only examine the complexity difference of the signals under a single sampling frequency.We developed a technique to measure the multifractal characteristic parameter intimately associated with physiological activities through a frequency scale factor.This parameter is highly sensitive to physiological and pathological status.Mice received various drugs to imitate different physiological and pathological conditions,and the distributions of mass exponent spectrum curvature with scale factors from the electrocardiogram (ECG) signals of healthy and drug injected mice were determined.Next,we determined the characteristic frequency scope in which the signal was of the highest complexity and most sensitive to impaired cardiac function,and examined the relationships between heart rate,heartbeat dynamic complexity,and sensitive frequency scope of the ECG signal.We found that all animals exhibited a scale factor range in which the absolute magnitudes of ECG mass exponent spectrum curvature achieve the maximum,and this range (or frequency scope) is not changed with calculated data points or maximal coarse-grained scale factor.Further,the heart rate of mice was not necessarily associated with the nonlinear complexity of cardiac dynamics,but closely related to the most sensitive ECG frequency scope determined by characterization of this complex dynamic features for certain heartbeat conditions.Finally,we found that the health status of the hearts of mice was directly related to the heartbeat dynamic complexity,both of which were positively correlated within the scale factor around the extremum region of the multifractal parameter.With increasing heart rate,the sensitive frequency scope increased to a relatively high location.In conclusion,these data provide important theoretical and practical data for the early diagnosis of cardiac disorders. 展开更多
关键词 ECG MULTIFRACTALITY COMPLEXITY frequency scale factor characteristic frequency
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GENERALIZED p-VALUES FOR TESTING REGRESSION COEFFICIENTS IN PARTIALLY LINEAR MODELS
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作者 Huimin HU Xingzhong XU Guoying LI 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2010年第6期1118-1132,共15页
The one-sided and two-sided hypotheses about the parametric component in partially linear model are considered in this paper. Generalized p-values are proposed based on fiducial method for testing the two hypotheses a... The one-sided and two-sided hypotheses about the parametric component in partially linear model are considered in this paper. Generalized p-values are proposed based on fiducial method for testing the two hypotheses at the presence of nonparametric nuisance parameter. Note that the nonparametric component can be approximated by a linear combination of some known functions, thus, the partially linear model can be approximated by a linear model. Thereby, generalized p-values for a linear model are studied first, and then the results are extended to the situation of partially linear model. Small sample frequency properties are analyzed theoretically. Meanwhile, simulations are conducted to assess the finite sample performance of the tests based on the proposed p-values. 展开更多
关键词 Fiducial inference frequency property generalized p-value hypothesis testing partially linear model.
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